The two line elements(TLEs),released by the North American Aerospace Defense Command(NORAD),are chosen for CubeSats' mission operators.Unfortunately,they have errors and other accompanied problems,which cause larg...The two line elements(TLEs),released by the North American Aerospace Defense Command(NORAD),are chosen for CubeSats' mission operators.Unfortunately,they have errors and other accompanied problems,which cause large deviations in the in-track component.When a TLE value is available at a certain epoch,the dominant error is the angular error.It is proposed to correct the angular error by solving-for the mean argument of latitude at the desired epoch.A batch least squares technique and range rate measurements are used for the correction process.With the assistance of satellite tool kit(STK)software and Matlab,a simulation to verify the orbit determination(OD)technique is implemented.This paper provides an angular correction low cost OD method and presents a complete analysis for various test cases.This approach maintains high accuracy in cross-track and radial and makes great improvement in in-track at the same time,but it is exclusive for circular orbits.When it is applied to an elliptical orbit,the error will be unacceptable.Therefore,the angular error is corrected using the longitude of periapsis which totally mitigates the error at the epoch under consideration.For inclinations less than 20 o,the mean longitude is preferred for the angular correction as it provides more accuracy compared with the mean argument of latitude.展开更多
The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit(GEO) satellite and Inclining GeoSynchronous Orbit(IGSO) satellite.The Combined-GEO-IGSO constellation can integrate the advantages of...The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit(GEO) satellite and Inclining GeoSynchronous Orbit(IGSO) satellite.The Combined-GEO-IGSO constellation can integrate the advantages of GEO and IGSO to achieve regional coverage.In order to discuss the performances of the Combined-GEO-IGSO constellation,the performances of coverage,elevation,diversity,and transmission are simulated in China and surrounding regions by Satellite Tool Kit(STK).The simulation results show that:the combined constellation can reach higher multi-satellite coverage and higher communication elevation in China and surrounding areas;the Doppler shift,delay,and propagation loss of this constellation have little impact on the system.As regional coverage constellation,the Combined-GEO-IGSO is feasible.展开更多
To provide backup and supplementation for the Global Navigation Satellite System(GNSS),Doppler shift from Low Earth Orbit(LEO)satellites can be used as signals of opportunity to provide positioning,navigation,and timi...To provide backup and supplementation for the Global Navigation Satellite System(GNSS),Doppler shift from Low Earth Orbit(LEO)satellites can be used as signals of opportunity to provide positioning,navigation,and timing service.In this contribution,we frst investigate the model and performance of instantaneous velocity determination and positioning with LEO satellites.Given a LEO constellation with 288 satellites,we simulate Doppler shift observations at nine multi-GNSS experiment stations.Owing to the lower orbit,the performance of LEO velocity determination is much more sensitive to the initial receiver position error than that of GNSS.Statistical results show that with the initial receiver position error increased from 0.1 to 10 m,the Root Mean Square Errors(RMSEs)increase from 0.73 to 2.65 cm/s,0.68 to 2.96 cm/s,and 1.67 to 4.15 cm/s in the east,north,and up directions,respectively.The performances with GPS are compared with GPS+LEO,and it is found that LEO Doppler shift observations contribute to GPS velocity determination.As for LEO Doppler positioning,even if more than 30 visible LEO satellites are available,the position dilution of precision values can reach several hundreds.Assuming that the error of LEO Doppler measurements is 0.01 m/s,the instantaneous Doppler positioning accuracy can achieve about a few meters,which is comparable to that of GNSS pseudorange positioning.A constant velocity model is adopted for state transition.Static LEO Doppler positioning results show that an accuracy at centimeter to decimeter level can be achieved after solution convergence.For a static simulated kinematic positioning test,the RMSEs range from a few decimeters to several meters in diferent regions by giving diferent constraints.For a dynamic positioning test,the RMSEs are about 2–3 m in high latitude region.展开更多
基金supported by the Research Fund for the Doctoral Program of Higher Education of China (No.20113219110025)
文摘The two line elements(TLEs),released by the North American Aerospace Defense Command(NORAD),are chosen for CubeSats' mission operators.Unfortunately,they have errors and other accompanied problems,which cause large deviations in the in-track component.When a TLE value is available at a certain epoch,the dominant error is the angular error.It is proposed to correct the angular error by solving-for the mean argument of latitude at the desired epoch.A batch least squares technique and range rate measurements are used for the correction process.With the assistance of satellite tool kit(STK)software and Matlab,a simulation to verify the orbit determination(OD)technique is implemented.This paper provides an angular correction low cost OD method and presents a complete analysis for various test cases.This approach maintains high accuracy in cross-track and radial and makes great improvement in in-track at the same time,but it is exclusive for circular orbits.When it is applied to an elliptical orbit,the error will be unacceptable.Therefore,the angular error is corrected using the longitude of periapsis which totally mitigates the error at the epoch under consideration.For inclinations less than 20 o,the mean longitude is preferred for the angular correction as it provides more accuracy compared with the mean argument of latitude.
基金Supported by the National Natural Science Foundation of China (No. 60972061,No. 60972062,and No. 61032004)the National High Technology Research and Development Program of China ("863" Program) (No. 2008AA12A204)the Natural Science Foundation of Jiangsu Province(BK2009060)
文摘The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit(GEO) satellite and Inclining GeoSynchronous Orbit(IGSO) satellite.The Combined-GEO-IGSO constellation can integrate the advantages of GEO and IGSO to achieve regional coverage.In order to discuss the performances of the Combined-GEO-IGSO constellation,the performances of coverage,elevation,diversity,and transmission are simulated in China and surrounding regions by Satellite Tool Kit(STK).The simulation results show that:the combined constellation can reach higher multi-satellite coverage and higher communication elevation in China and surrounding areas;the Doppler shift,delay,and propagation loss of this constellation have little impact on the system.As regional coverage constellation,the Combined-GEO-IGSO is feasible.
基金the Fund of National Key Research and Development Program of China(No.2022YFB3903902)the National Science Fund for Distinguished Young Scholars(No.41825009)the Key Research and Development Program of Hubei Province(No.2022BAA054).
文摘To provide backup and supplementation for the Global Navigation Satellite System(GNSS),Doppler shift from Low Earth Orbit(LEO)satellites can be used as signals of opportunity to provide positioning,navigation,and timing service.In this contribution,we frst investigate the model and performance of instantaneous velocity determination and positioning with LEO satellites.Given a LEO constellation with 288 satellites,we simulate Doppler shift observations at nine multi-GNSS experiment stations.Owing to the lower orbit,the performance of LEO velocity determination is much more sensitive to the initial receiver position error than that of GNSS.Statistical results show that with the initial receiver position error increased from 0.1 to 10 m,the Root Mean Square Errors(RMSEs)increase from 0.73 to 2.65 cm/s,0.68 to 2.96 cm/s,and 1.67 to 4.15 cm/s in the east,north,and up directions,respectively.The performances with GPS are compared with GPS+LEO,and it is found that LEO Doppler shift observations contribute to GPS velocity determination.As for LEO Doppler positioning,even if more than 30 visible LEO satellites are available,the position dilution of precision values can reach several hundreds.Assuming that the error of LEO Doppler measurements is 0.01 m/s,the instantaneous Doppler positioning accuracy can achieve about a few meters,which is comparable to that of GNSS pseudorange positioning.A constant velocity model is adopted for state transition.Static LEO Doppler positioning results show that an accuracy at centimeter to decimeter level can be achieved after solution convergence.For a static simulated kinematic positioning test,the RMSEs range from a few decimeters to several meters in diferent regions by giving diferent constraints.For a dynamic positioning test,the RMSEs are about 2–3 m in high latitude region.
